What is a 2 photon laser?

Two-photon excitation microscopy (TPEF or 2PEF) is a fluorescence imaging technique that allows imaging of living tissue up to about one millimeter in thickness, with 0.64 μm lateral and 3.35 μm axial spatial resolution.

What is two-photon fluorescence?

Two-photon fluorescence microscopy allows three-dimensional imaging of biological specimens in vivo. Compared with confocal microscopy, it offers the advantages of deeper tissue penetration and less photodamage but has the disadvantage of slightly lower resolution.

Is Raman a two-photon process?

Raman scattering is one of a group of two-photon processes in which one photon is absorbed and another is emitted essentially simultaneously.

How does a two-photon microscope work?

When using two-photon microscopy, two or three photons of a higher wavelength do the work of one: When they hit the fluorophore at the very same time (typically within several femtoseconds), they are absorbed, resulting in fluorophore excitation and emission of light.

What are two photons?

First described by Maria Goeppert-Mayer in 1931, two-photon absorption is the concept that two photons of identical or different frequencies can excite a molecule from one energy state (usually the ground state) to a higher energy state in a single quantum event.

How does 2 photon calcium imaging work?

Two-photon calcium imaging has been widely used to image the activity of neurons in awake behaving animals. Neurons are loaded with a calcium-sensitive dye or, more commonly, made to express a genetically encoded calcium indicator, such that their fluorescence signal reflects spiking activity of the neurons.

What is two-photon photoluminescence?

Two-photon photoluminescence (TPPL) is an emission process which can take place when an emitter absorbs two photons of low energy simultaneously and emits a photon of high energy.

What is two-photon resonance?

Two-photon absorption is one of a variety of two-photon processes. In this specific process, two photons are absorbed by a sample simultaneously. Neither photon is at resonance with the available energy states of the system, however, the combined frequency of the photons is at resonance with an energy state.

Why is two-photon absorption a third order process?

Two-photon absorption (TPA) is a third order nonlinear optical phenomenon in which a molecule absorbs two photons at the same time. The transition energy for this process is equal to the sum of the energies of the two photons absorbed.

What is the benefit of two-photon microscopy?

The principal advantages of two-photon microscopy are reduced phototoxicity, increased imaging depth, and the ability to initiate highly localized photochemistry in thick samples.

What is two-photon polymerization?

Two-photon polymerization is a non-linear optical process based on the simultaneous absorption of two photons in a photosensitive material (photoresist). This process changes the photosensitive material, i.e. it leads to a polymerization by activating so-called photo-initiators in the resist.

Why two-photon excitation is non-linear?

In two-photon excitation, the relationship is non-linear (quadratic) as the fluorescence intensity is dependent on the square of the number of photons arriving at the fluorophore due to there being multiple photons involved (the probability of absorbing the first photon multiplied by the probability of absorbing the …